I love the Antigua line of guns, I have both branches on my two-weapon loadout as I build my way (slowly and painfully without CE) to 5*, and both are exceptional weapons as a Gunslinger. They're fast, have a high DPS rating, accurate, wicked cool looking, and don't get in the way of what other party members are doing since they have no knockback and little in the way of particle blindage. I love these two guns to death.
I'm hesitant to get an Alchemer because of the two-shot clip issue, and the fact that these two guns cover my Elemental/Shadow needs. Is it really worth getting an Alchemer of some sort if I have these two guns already?
My Gunslinger loadout was going to be Argent Peacemaker, Sentenza, Blitz Needle, and Shivermist.
Get one and try it out, although their damage isn't amazing until 4-5* simply because of the ricochet mechanic.
I have silversix and although its a fine weapon, it doesn't suit the way I enjoy gunning.
Gameplay wise, if you need to craft something else that would actually benefit you, such as the chaos set or the gunslinger gear, should probably do that first since you have your damage type covered.